1. Technical Field
Photoresist polymers and photoresist compositions containing the same are disclosed. More specifically, photoresist polymers and photoresist compositions containing the same are disclosed that may improve line edge roughness (hereinafter, referred to as ‘LER’) in a photoresist process using light sources of far ultraviolet regions of 190 nm and 157 nm.
2. Description of the Related Art
In order to be used for ArF and VUV (vacuum ultraviolet) resists, photoresist polymers and photoresist compositions are required to have low light absorbance at wavelengths of 193 nm and 157 nm, excellent etching resistance and adhesive property on the substrate, and to be developed with TMAH solution of 2.38 wt % and 2.6 wt %.
Recently, much research has been conducted on resins having a high transparency at 248 nm and 193 nm wavelengths and dry etching resistance similar to novolac resin.
Since the thickness of resist materials becomes thinner as circuits of semiconductor devices become more microscopic, improvement of LER of patterns has been promptly required.
The LER occurs more frequently in ArF resist patterns than in conventional KrF or i-line resist patterns. The conventional KrF or i-line resist materials include acidic alcohol groups while most ArF resist materials do not include acidic alcohol group. As a result, since the ArF resist materials have low affinity to basic developing solutions, the LER occurs more frequently in the ArF resist materials.
This phenomenon occurs more severely when patterns are formed using chemically amplified photoresist. The LER degrades stability and yield of semiconductor devices for performing a subsequent process.